Applicant: Tommy V. Vo Project Summary / Abstract Regulation of gene expression is fundamental to human health and disease. The fact that gene misregulation is a hallmark characteristic of all cancers underscores the importance of maintaining the appropriate pattern of gene expression that defines various cell types. Work in the model fission yeast, Schizosaccharomyces pombe, has begun to reveal a highly complex, dynamic, and conserved model of genome-wide gene silencing where distinct modes of silencing are utilized at different regions of the genome. A common feature throughout all regions with transcriptional potential is the presence of RNA polymerase II (Pol II). Here, we propose to uncover how Pol II can serve as a signal integrator that directs a wide range of different silencing mechanisms across the genome to enable gene silencing. Using a combination of stable-isotope labeling with amino acids in cell culture (SILAC) and Precision nuclear run-on and sequencing (PRO-seq), we will comprehensively elucidate the role of paused Pol II in gene regulation. This work will help shed light into how different gene silencing pathways can be directed in healthy and diseased cells.